1. Field of the Invention
This invention relates to materials used to balance tires.
2. Description of the Prior Art
Tire balance is important for vehicle ride and stability and for customer satisfaction as well. Tires, wheels, rims, brake drums, rotors and hubs are all manufactured to a close tolerance for roundness, shape and balance. By assembling all these tolerances together, the probability of this assembly being out of balance is high. Wheel imbalance causes forces that result in vibration through the vehicle's steering, suspension and body. Imbalance is the cause of the majority of vibration complaints.
One method of solving tire imbalance is to use a free-flowing balancing material within the imbalanced tire. The material is first introduced at mounting or a mounted tire. The tire retains proper balance simply because the free-flowing material, the minuscule individual elements making up the material, inside the tire are distributed in such a way that evens out the heavy spot in the tire assembly. Glycol and fibres were first used about thirty years ago.
In the case of a rotating tire and wheel, a heavy spot creates a force away from the tire, but because it is anchored by the axle, an opposite force is created within the tire as the forces flexes the suspension. This will draw a sufficient quantity of the balancing material in the direction of the opposite force until the heavy spot is neutralized. In currently available material, the remaining balancing material spreads itself evenly around the inside of the tire, the material then remains in place. When the vehicle stops, the conventional material falls away from its neutralizing position on the liner and falls to the bottom of the tire, and returns to a neutralizing position when the vehicle re-commences motion at highway speeds. Therefore, the whole process of re-balancing must recommence after every stop.
U.S. Pat. No. 5,766,501 to Heffernan et al. is one such traditional balancing material that works in the conventional manner described above. In this disclosure, Heffernan teaches a balancing material having a composition to reduce friction of the overall balancing material to ensure the material retains free-flowing characteristics when installed into a tire. The composition disclosed therein still, however, has undesirable qualities.
Unfortunately, this constant "on the liner" and "off the liner" motion of conventional balancing materials has problems; for instance, some of the currently available balancing materials deteriorate through this constant "on"-"off" motion into dust particles. This deterioration causes mounting and dismounting problems for tire installers as the resulting dust is undesirable because the dust leaves a coat on the wheel and the tire mounting surface. Further still, the deterioration clogs the tire valve seat thereby causing an air leak. The end result is that conventional balancing materials do not produce a constant balanced tire as they have to recommence the re-balancing process after every stop. During the gradual time the material is relocating to or from the balancing positions, the tire is out of balance.
Another problem that exists with currently available balancing materials is that the materials are abrasive in nature. The abrasive characteristic of currently available materials along with the on and off the liner action of the materials causes undesirable wearing down from the inside of the tire. The absorption of moisture is another problem facing currently available materials. By the dust absorbing moisture these materials clump together. As a result of this moisture clumping, conventional materials tend not to position themselves in correct neutralizing/counterbalancing positions. Further still, another problem encountered with some currently available materials is that the materials sometimes react to the alloyed wheels. One such traditional material has brass tracings that react to aluminum wheels.
Therefore, there exists a need to provide an alternative balancing material to overcome some of the drawbacks of currently available materials.